Along with surging shares of newly public tech outfits, Silicon Valley CEOs in search of the “next big thing” are driving up prices for private tech companies, giving rise to talk of another bubble.

Companies spent way more to acquire private US tech companies last year even though the number of acquisitions was down compared to the previous year’s peak, a new report shows.

In 2013, $111.8 billion changed hands in private tech company transactions, a 34 percent jump from 2012, according to PrivCo, which conducts due diligence on private companies.

Meanwhile, the total number of deals involving privately held tech companies dropped by 31 percent, suggesting that fewer players are participating in an increasingly frothy market.

This has industry watchers worried about two tech bubbles: one in publicly traded stocks and the other in privately held acquisition targets.

“Everything is consistent with the first signs of a tech bubble,” said PrivCo founder and CEO Sam Hamadeh.

Leading Silicon Valley’s startup shopping spree is Marissa Mayer. Yahoo!’s spender-in-chief ranks as the most active dealmaker after buying 22 companies last year — an average of one every 16 days.

The Sunnyvale, Calif., company spent $1.21 billion in the space last year, more than rivals such as Google, at $1.95 billion, but less than venture capital giants like Silver Lake Partners, which spent $25 billion — most of it to take PC-maker Dell private.

While Yahoo! wasn’t the top spender in terms of total dollars, Mayer was the most willing to pay a lot for startups with only a promise of future revenue.

On average, Yahoo! paid a multiple of 84 times revenue for private tech outfits, according to PrivCo’s report. That compares to the 69.8 average revenue multiple for Amazon, which ranked second.

If some investors questioned Mayer’s buying binge last year, including $1 billion for microblogging startup Tumblr and $30 million for news-reading app Summly, just wait until she has more than $10 billion burning a hole in her purse.

A big moment for Mayer will come after Alibaba, China’s e-commerce leader, completes one of the biggest initial public offerings in US history. The IPO triggers a provision requiring Yahoo! to sell about 40 percent of its stake in Alibaba.

“All of Wall Street and Silicon Valley is waiting — and salivating over — what these multi-billions are going to buy,” Hamadeh said of Yahoo!, which is expected to reap between $10 billion and $15 billion for selling down part of its 24 percent Alibaba stake.

“Everyone is waiting to present her with the next Whatsapp,” Hamadeh said, referring to Facebook’s massive $19 billion messaging app acquisition earlier this year.

Indeed, Facebook CEO Mark Zuckerberg has also been contributing to Silicon Valley’s private tech bubble with his own buying binge.

In addition to forking over $19 billion for Whatsapp, Zuckerberg plopped down a whopping $2 billion for Oculus VR, a startup that makes virtual reality gaming goggles that are still in development.

Investors are also questioning whether Apple CEO Tim Cook has caught spendthrift fever now that the tech titan is in talks to pay $3.2 billion for headphone company Beats Entertainment.